Hyper-precise positioning and communications system and network

ABSTRACT

A hyper-precise positioning and communications (HPPC) system and network are provided. The HPPC system is a next-generation positioning technology that promises a low-cost, high-performance solution to the need for more sophisticated positioning technologies in increasingly cluttered environments. The HPPC system is a joint positioning-communications radio technology that simultaneously performs relative positioning and secure communications. Both of these tasks are performed with a single, co-use waveform, which efficiently utilizes limited resources and supports higher user densities. Aspects of this disclosure include an HPPC system for a network which includes an arbitrary number of network nodes (e.g., radio frequency (RF) devices communicating over a joint positions-communications waveform). As such, networking protocols and design of data link and physical layers are described herein. An exemplary embodiment extends the HPPC system for use with existing cellular networks, such as third generation partnership project (3GPP) long term evolution (LTE) and fifth generation (5G) networks.

RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.16/787,300, filed Feb. 11, 2020, subsequently issued as U.S. Pat. No.11,172,334 on Nov. 9, 2021, which claims the benefit of U.S. ProvisionalPatent Application Ser. No. 62/803,800, filed Feb. 11, 2019, wherein theentire disclosures of the foregoing applications and patent are herebyincorporated by reference herein.

This application is related to International Patent Application No.PCT/US2018/066763, filed Dec. 20, 2018, entitled “PHASE-ACCURATE VEHICLEPOSITIONING SYSTEMS AND DEVICES,” the disclosure of which is herebyincorporated herein by reference in its entirety.

FIELD OF THE DISCLOSURE

This disclosure relates to systems and devices which provide vehiclepositional information and communications using radio networks.

BACKGROUND

Positioning systems are used to provide information regarding relativepositions of objects. For example, vehicle positioning systems assistoperators in travel and operation of air and ground vehicles. Forexample, aircraft positioning systems assist operators of variousaircraft, particularly in critical tasks such as landing. Suchpositioning systems enable takeoff and landing in low visibilityconditions through autonomous systems or presenting pilots withinformation which enables more accurate manual operation. Aircraftpositioning systems are also critical for remote controlled tasks, suchas drone operation.

Traditionally, vehicle positioning systems have required tradeoffsbetween accuracy of measurement and spectral efficiency—where moreaccurate positioning has required higher-bandwidth signals. Modernvehicle systems demand increasingly sophisticated positioningtechnologies in increasingly cluttered environments. In addition,vehicle positioning signals have traditionally been segregated fromcommunications signals, requiring dedicated spectrum for each. Thus,legacy radio systems do not support modern performance requirements oruser densities.

SUMMARY

A hyper-precise positioning and communications (HPPC) system and networkare provided. The HPPC system is a next-generation positioningtechnology that promises a low-cost, high-performance solution to theneed for more sophisticated positioning technologies in increasinglycluttered environments. This technology offers extreme ranging precision(e.g., <5 centimeters (cm)) with minimal bandwidth (e.g., 10 megahertz(MHz)), a secure communications link to protect against cyberattacks, asmall form factor that enables integration into numerous platforms, andminimal resource consumption which supports high-density networks. Thissystem operates with minimal infrastructure and is highly reconfigurableto execute a variety of missions.

The HPPC system is a joint positioning-communications radio technologythat simultaneously performs relative positioning and securecommunications. Both of these tasks are performed with a single, co-usewaveform, which efficiently utilizes limited resources and supportshigher user densities. Network nodes within an HPPC network perform thepositioning task using a cooperative, point-to-point protocol toestimate position states (e.g., relative position and orientation) ofthe network nodes in the network. The communications task distributespositioning information (e.g., time information for clock alignment,estimated position states, etc.) and/or additional information betweennetwork nodes and secures the positioning task against cyberattacks.This technology may be installed in ground stations, ground vehicles,unmanned aerial systems (UASs), and airborne vehicles, enabling ahighly-mobile, reconfigurable network.

Aspects of this disclosure include an HPPC system for a network whichincludes an arbitrary number of network nodes (e.g., radio frequency(RF) devices communicating over a joint positioning-communicationswaveform). As such, networking protocols and design of data link andphysical layers are described herein. An exemplary embodiment extendsthe HPPC system for use with existing cellular networks, such as thirdgeneration partnership project (3GPP) long term evolution (LTE) andfifth generation (5G) networks.

This technology has numerous applications to modern vehicle systems.High-precision relative positioning enables applications such ascollision avoidance, automated landing, navigation, and formationcontrol. Secure network communications enable a distributed knowledgebase, real-time traffic conditions, and air traffic management, and whencombined with the positioning task maintains distributed coherencebetween users. The system flexibility allows quick and easy installationin areas without existing coverage, providing immediate support insituations such as disaster relief or forward operating bases. Thistechnology further supports automation of vehicular transport byproviding a cooperative medium between users, enablingvehicle-to-vehicle communications and remote control.

An exemplary embodiment of this disclosure provides a method for sendingjoint positioning and communications. The method includes estimating aposition state relative to a network node and generating a jointpositioning-communications waveform. The jointpositioning-communications waveform includes a preamble; a data payload;a first positioning sequence; and a second positioning sequence. Themethod further includes transmitting a first signal comprising the jointpositioning-communications waveform, wherein the data payload of thefirst signal comprises the position state.

Another exemplary embodiment of this disclosure provides a method forreceiving and processing joint positioning and communications. Themethod includes receiving a first signal comprising a jointpositioning-communications waveform from a network node, the jointpositioning-communications waveform comprising: a preamble; a datapayload, wherein the data payload of the first signal comprises a firstposition state of the network node; a first positioning sequence; and asecond positioning sequence. The method further includes estimating asecond position state relative to the network node from the firstsignal.

Another exemplary embodiment of this disclosure provides a network forjoint positioning and communications. The network includes a firstnetwork node, comprising: a first signal transceiver configured tocommunicate wirelessly with a second network node and a first signalprocessor. The first signal processor is operable to estimate a firstposition state of the first network node relative to the second networknode and generate a joint positioning-communications waveform. The jointpositioning-communications waveform includes a preamble; a data payload;a first positioning sequence; and a second positioning sequence. Thefirst signal processor is further operable to cause the first signaltransceiver to transmit a first signal comprising the jointpositioning-communications waveform, wherein the data payload of thefirst signal comprises the first position state.

Those skilled in the art will appreciate the scope of the presentdisclosure and realize additional aspects thereof after reading thefollowing detailed description of the preferred embodiments inassociation with the accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The accompanying drawing figures incorporated in and forming a part ofthis specification illustrate several aspects of the disclosure, andtogether with the description serve to explain the principles of thedisclosure.

FIG. 1 is a schematic diagram of an exemplary network for jointpositioning and communications, referred to herein as a hyper-precisepositioning and communications (HPPC) network.

FIG. 2 is a schematic diagram of the HPPC network of FIG. 1 ,illustrating estimation of position information based on exchangingradio frequency (RF) signals between a first network node and a secondnetwork node.

FIG. 3A is a schematic diagram of the HPPC network, illustrating a clockoffset between the first network node (e.g., node A) and the secondnetwork node (e.g., node B) of FIG. 2 .

FIG. 3B is a flow diagram illustrating an exemplary timing exchangemodel at node A of FIG. 3A for two cycles using a jointpositioning-communications waveform.

FIG. 3C is a flow diagram illustrating the timing exchange model of FIG.3B at node A of FIG. 3A for two frames, referenced with respect to anestimation and tracking model.

FIG. 4A is a schematic diagram of interactions between network nodes ofthe HPPC network of FIG. 2 , illustrating an example protocol of thejoint positioning-communications waveform.

FIG. 4B is a schematic diagram of an exemplary structure of the jointpositioning-communications waveform using the protocol of FIG. 4A.

FIG. 4C is a schematic diagram of another exemplary structure of thejoint positioning-communications waveform using the protocol of FIG. 4A.

FIG. 5 is a schematic diagram of physical layer components of the jointpositioning-communications waveform of FIGS. 4B and 4C.

FIG. 6A is a schematic diagram of a structure of a long term evolution(LTE) frame, which can be adapted to include the jointpositioning-communications waveform of the HPPC network of FIGS. 1-5 .

FIG. 6B is a schematic diagram of a structure of a slot in the LTE frameof FIG. 6A.

FIG. 6C is a schematic diagram of resource blocks and resource elementsof the LTE frame of FIG. 6A.

FIG. 7 is a schematic diagram of a generalized representation of anexemplary computer system that could be used to perform any of themethods or functions described herein, such as receiving, processing,and/or sending joint positioning-communications waveforms.

DETAILED DESCRIPTION

The embodiments set forth below represent the necessary information toenable those skilled in the art to practice the embodiments andillustrate the best mode of practicing the embodiments. Upon reading thefollowing description in light of the accompanying drawing figures,those skilled in the art will understand the concepts of the disclosureand will recognize applications of these concepts not particularlyaddressed herein. It should be understood that these concepts andapplications fall within the scope of the disclosure and theaccompanying claims.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the present disclosure. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present.

Relative terms such as “below” or “above” or “upper” or “lower” or“horizontal” or “vertical” may be used herein to describe a relationshipof one element, layer, or region to another element, layer, or region asillustrated in the Figures. It will be understood that these terms andthose discussed above are intended to encompass different orientationsof the device in addition to the orientation depicted in the Figures.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”“comprising,” “includes,” and/or “including” when used herein specifythe presence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure belongs. It willbe further understood that terms used herein should be interpreted ashaving a meaning that is consistent with their meaning in the context ofthis specification and the relevant art and will not be interpreted inan idealized or overly formal sense unless expressly so defined herein.

A hyper-precise positioning and communications (HPPC) system and networkare provided. The HPPC system is a next-generation positioningtechnology that promises a low-cost, high-performance solution to theneed for more sophisticated positioning technologies in increasinglycluttered environments. This technology offers extreme ranging precision(e.g., <5 centimeters (cm)) with minimal bandwidth (e.g., 10 megahertz(MHz)), a secure communications link to protect against cyberattacks, asmall form factor that enables integration into numerous platforms, andminimal resource consumption which supports high-density networks. Thissystem operates with minimal infrastructure and is highly reconfigurableto execute a variety of missions.

The HPPC system is a joint positioning-communications radio technologythat simultaneously performs relative positioning and securecommunications. Both of these tasks are performed with a single, co-usewaveform, which efficiently utilizes limited resources and supportshigher user densities. Network nodes within an HPPC network perform thepositioning task using a cooperative, point-to-point protocol toestimate position states (e.g., relative position and orientation) ofthe network nodes in the network. The communications task distributespositioning information (e.g., time information for clock alignment,estimated position states, etc.) and/or additional information betweennetwork nodes and secures the positioning task against cyberattacks.This technology may be installed in ground stations, ground vehicles,unmanned aerial systems (UASs), and airborne vehicles, enabling ahighly-mobile, reconfigurable network.

Aspects of this disclosure include an HPPC system for a network whichincludes an arbitrary number of network nodes (e.g., radio frequency(RF) devices communicating over a joint positioning-communicationswaveform). As such, networking protocols and design of data link andphysical layers are described herein. An exemplary embodiment extendsthe HPPC system for use with existing cellular networks, such as thirdgeneration partnership project (3GPP) long term evolution (LTE) andfifth generation (5G) networks.

This technology has numerous applications to modern vehicle systems.High-precision relative positioning enables applications such ascollision avoidance, automated landing, navigation, and formationcontrol. Secure network communications enable a distributed knowledgebase, real-time traffic conditions, and air traffic management, and whencombined with the positioning task maintains distributed coherencebetween users. The system flexibility allows quick and easy installationin areas without existing coverage, providing immediate support insituations such as disaster relief or forward operating bases. Thistechnology further supports automation of vehicular transport byproviding a cooperative medium between users, enablingvehicle-to-vehicle communications and remote control.

FIG. 1 is a schematic diagram of an exemplary network for jointpositioning and communications, referred to herein as an HPPC network10. In the HPPC network 10, RF signals 12 are exchanged between networknodes using a joint positioning-communications waveform in order tofacilitate estimation of position information of the network nodes. Inthe illustrated example, the network nodes include a base station 14(e.g., a first network node) and an aircraft 16 (e.g., a second networknode, such as a UAS). In an exemplary aspect, the aircraft 16 canestimate its position information (e.g., range, position, orientation,and/or acceleration) relative to the base station 14 from the exchangedRF signals 12. In some examples, the base station 14 (and eachadditional network node in the HPPC network 10) can likewise estimatesuch position information.

The position information of the aircraft 16 can be used for varioustasks, such as formation flying, coordination of safe flight paths,takeoff, landing, and taxiing. In some examples, the RF signals 12 canalso carry payload data for communications between the aircraft 16 andthe base station 14 or other network nodes in the HPPC network 10. Suchpayload data may facilitate additional tasks, such as coordination of aformation of aircraft 16.

As illustrated in FIG. 1 , the base station 14 can be a distributed basestation having multiple antennas 18 to provide more accurate and/ordetailed position information (e.g., in addition to range, multipleantennas can provide position and orientation estimation). Similarly,the aircraft 16 can have a multi-antenna RF transceiver. In anillustrative example, the aircraft 16 has a four-antenna transceiver andthe base station 14 has three antennas 18, such that twelve RF signals12 are exchanged between the base station 14 and the aircraft 16 tofacilitate improved estimation of position information.

In an exemplary aspect, the HPPC network 10 operates with a 10 MHzbandwidth and maintains a ranging standard deviation below 5 cm for upto 2 kilometers (km) of range. In controlled configurations, thisdeviation can be driven as low as 1 millimeter (mm). This capability isfacilitated by a phase accurate time-of-arrival (ToA) estimationtechnique and a distributed phase-coherence algorithm, described furtherbelow.

It should be understood that while FIG. 1 is described with respect toaircraft 16 in particular, exemplary embodiments may include other typesof RF devices, including vehicles. For example, a radio-bearingautomobile in the HPPC network 10 may facilitate relevant positioningtasks, such as parking, street navigation, and awareness of othervehicles for passing, accelerating, stopping, and so on. A radio-bearingship in the HPPC network 10 can facilitate relevant positioning taskssuch as navigation, formation travel, collision avoidance, docking, andso on. Embodiments of the present disclosure implemented in suchvehicles may be used for assisted operation, remote control, autonomoussystems, and so on. In other examples, the network nodes of the HPPCnetwork 10 can include an automobile, ship, train, or other vehicle, ornon-vehicular applications where position information is needed orbeneficial.

FIG. 2 is a schematic diagram of the HPPC network 10 of FIG. 1 ,illustrating estimation of position information based on exchanging RFsignals 12 between a first network node 20 and a second network node 22.Each network node 20, 22 can be a base station (e.g., the first networknode can be the base station 14 of FIG. 1 ) or a vehicle (e.g., thesecond network node can be the aircraft 16 of FIG. 1 ). In addition,each network node 20, 22 in the HPPC network 10 can also include or beimplemented as an RF device. For example, the second network node 22includes an RF transceiver 24. The RF transceiver 24 is coupled to oneor more antennas 26, through which the RF transceiver 24 can communicatewirelessly with the first network node 20 (e.g., at each of one or moreantennas 28).

In an exemplary aspect, the RF transceiver 24 includes an RF receiverand an RF transmitter for communicating wirelessly over RF signals 12.In some examples, the RF transceiver 24 can communicate over cellular ornon-cellular RF frequency bands, citizens broadband radio service (CBRS)frequency bands, over microwave frequency bands, over millimeter wave(mmWave) frequency bands, over optical frequency bands, and so on. Insome examples, the RF transceiver 24 exchanges signals having a narrowbandwidth, such as 10 MHz or less. In some examples, the RF transceiver24 exchanges signals over an LTE, 5G, or other 3GPP cellularcommunication signal.

As illustrated in FIG. 2 , the RF transceiver 24 can couple to an arrayof antennas 26. Each of the antennas 26 of the second network node 22may exchange RF signals 12 with each of multiple antennas 28 of thefirst network node 20 (and additional network nodes in the HPPC network10). The second network node 22 further includes a signal processor 30coupled to the RF transceiver 24 to process the RF signals 12 exchangedwith the first network node 20. By processing the RF signals 12, thesignal processor 30 can estimate a position state of the second networknode 22 based on relative distances between the antennas 26 of thesecond network node 22 and each of the antennas 28 of the first networknode 20. The position state can estimate relative range, position,velocity, acceleration, bearing, altitude and/or orientation of thesecond network node 22. The position state estimates can be fused withadditional information (e.g., additional information received via theHPPC network 10, inertial measurement data, sensor data) to refine therelative and/or absolute position of the second network node 22.

Aspects of the present disclosure describe the HPPC network 10, whichincludes a plurality of such network nodes 20, 22 that simultaneouslyperform positioning and communications tasks. Simultaneouslyimplementing communications and positioning tasks enables numeroussecondary functions with fewer resources. Network nodes 20, 22 withinthe HPPC network 10 communicate with their neighbors whilesimultaneously estimating the position and orientation of each nearbynetwork node 20, 22.

Position estimation is performed by estimating the time-of-flight (ToF)between each transmit-receive antenna pair (e.g., an antenna 28 of thefirst network node 20 and an antenna 26 of the second network node 22).These ToF estimates are converted into distance estimates, which driveposition and orientation estimators (e.g., the position state). ToFestimation is enabled by the simultaneous communications link (e.g., viathe RF signals 12), in which time information is shared between networknodes, which in turn drives a synchronization algorithm that preciselyaligns their clocks. This alignment enables high-precision ToFestimation, thus enabling high-precision position and orientationestimation.

In this regard, system design of the HPPC network 10 includes thefollowing:

1. Time-of-Flight Estimation: The HPPC positioning task is performed byestimating the ToF between each transmit-receive antenna pair betweentwo network nodes 20, 22. ToF is estimated by finding the differencebetween the transmit and receive times of the jointpositioning-communications waveform. The transmit time is known to thetransmitter, and shared with the receiver via the communications link.The receive time (ToA) is estimated by the receiver. ToA is estimated bycorrelating the received signal against a known reference sequence. Ifthe radio clocks are well aligned, the phase of the received signal maybe leveraged to improve the quality of this estimate well beyond itsintrinsic resolution. This is further described below with respect toFIGS. 3A and 3B.

2. Time Synchronization Algorithm: To achieve high-precision positionestimates, the radio clocks must be well aligned, which enableshigh-precision ToA estimation. A modern extension to the Network TimingProtocol (NTP) is developed which synchronizes two network nodes 20, 22operating in the HPPC network 10. This algorithm estimates the timeoffset and ToF between two network nodes 20, 22 as they alternatetransmitting and receiving. Derivatives of these variables are trackedand leveraged to refine these estimates. This provides the network nodes20, 22 with the necessary information to synchronize their clocks wellenough to achieve phase-accurate ToA estimation. This is furtherdescribed below with respect to FIG. 3C.

3. Joint Positioning-Communications Waveform Design: The positioning andcommunications tasks are performed simultaneously with a single co-usewaveform, as described further below with respect to FIG. 4A. A novelwaveform is designed that incorporates the necessary elements of eachtask. This waveform consists of a communications preamble,communications payload, communications postamble, positioning waveforms,and a second communications postamble. The preamble is a fixed sequenceand known to all receivers. The communications payload contains thestate space estimates produced by the synchronization algorithm, thetimestamp information necessary to estimate the ToF, and auxiliaryhardware information. In some examples, the positioning waveforms arepseudo-random waveforms that are transmitted from each antenna using acode-division duplexing (CDD) approach (as described with respect toFIG. 4B) or a time division duplexing (TDD) approach (as described withrespect to FIG. 4C), and are known to the receiver. The preamble andpostambles are used to make coarse and fine frequency offset estimatesfor the communications processing chain.

The HPPC network 10 further requires a medium access protocol thatcontrols how and when network nodes 20, 22 access the spectrum, and howresources are divided among network nodes 20, 22 within the HPPC network10. This includes regulating the length of each transmission, how oftenand in what frequency ranges each network node 20, 22 may transmit, andhow network nodes 20, 22 are added or removed from the HPPC network 10.This also includes consolidating data from multiple network nodes 20, 22and expressing it in a meaningful and useful representation. Anexemplary protocol using the waveform of FIGS. 4A-4C is described withrespect to FIG. 5 . An extension of the HPPC system for LTE and 5Gcellular communications networks is described further with respect toFIGS. 6A-6C.

FIG. 3A is a schematic diagram of the HPPC network 10, illustrating aclock offset between the first network node 20 (e.g., node A) and thesecond network node 22 (e.g., node B) of FIG. 2 . For illustrativepurposes, the first network node 22 (illustrated as node A) can beassumed to be stationary and tethered to the ground while the secondnetwork node 22 (illustrated as node B) is airborne, moving with avelocity {right arrow over (v)} and acceleration {right arrow over (a)}in a three-dimensional Cartesian space.

Nodes A and B are driven by independent clocks and they communicate overa single-input-single-output (SISO) line-of-sight environment. The twonodes sequentially exchange communications waveforms that includetransmit t_((⋅),Tx) and receive t_((⋅),Rx) timestamps. These timestampsare leveraged to estimate the stochastic processes, relative clockoffsets (T) and propagation time (e.g., ToF (τ)) between the two nodes.Radial velocity {dot over (τ)} and acceleration {umlaut over (τ)} actalong the dashed line. Proposed methods readily generalize to multiplenode networks operating on multi-antenna platforms.

FIG. 3B is a flow diagram illustrating an exemplary timing exchangemodel at node A of FIG. 3A for two cycles using a jointpositioning-communications waveform. Each cycle can span two frames, andthe cycles are separated by time L_(A), indicated by a dashed line.Designated master node A transmits the joint positioning-communicationswaveform to node B in the first frame, node B waits for an agreed frameseparation l and transmits it back to node A during the second frame.The transmit timestamp t_(B,Tx) ^((n)) is perceived by node A as {tildeover (t)}_(A,Tx) ^((n)) (shown in dashed line) and frame length l asl_(A) due to clock offset T.

FIG. 3C is a flow diagram illustrating the timing exchange model of FIG.3B at node A of FIG. 3A for two frames, referenced with respect to anestimation and tracking model.

With reference to FIGS. 3A-3C, the two nodes A and B sequentiallyexchange timing information via the joint positioning-communicationswaveform, which is then translated to corresponding timestamps usingphase-accurate ToA estimation methods. These timestamps are denoted byt_((⋅),(⋅)) ^((⋅)), in which the first subscript indicates the node atwhich the event occurs, the second subscript indicates if it was atransmit or receive event, and the superscript is an indication of frameduring which the event occurs. The transmit timestamps are assumed to beknown with certainty while the receive timestamps are a result ofphase-accurate ToA estimation, hence represented as {circumflex over(t)}_((⋅),Rx) ^((⋅)). Two successive frames comprise a cycle that isL^((⋅)) seconds (s) long and is represented as {(k), (k+1)} where thesuccessive frames (k) and (k+1) are l^((⋅)) s apart. Despite scheduling,the nodes disagree on time hence making frame length dependent on theevaluating node l_(A) ^((⋅)) or l_(B) ^((⋅)).

Timing Exchange and Position State Estimation

With continuing reference to FIG. 3B, during a cycle {(n−1), (n)},designated master node A transmits a communication packet to node B inthe first frame (n−1), node B waits for an agreed frame separation l andtransmits a packet to node A during the second frame (n). Each packetcomprises a transmit time stamp t_((⋅),Tx) of the transmitting nodealong with communication payload. Exemplary embodiments are concernedwith estimating clock offset (T) and relative ToF (τ) between the twonodes for the cycle containing (n−1)^(th) and (n)^(th) frames whilemaking an assumption that estimates of these parameters for previouscycles are available.

For a transmission from node A to node B, during frame (n−1), node Bwill receive the signal at time:{circumflex over (t)} _(B,Rx) ^((n-1)) =t _(A,Tx) ^((n-1))+{circumflexover (τ)}^((n-1)) −{circumflex over (T)} ^((n-1))  Equation 1whereas for a transmission from node B to node A, during frame (n), nodeA will receive the signal at time:{circumflex over (t)} _(A,Rx) ^((n)) =t _(B,Tx) ^((n))+{circumflex over(τ)}^((n)) +{circumflex over (T)} ^((n))  Equation 2

The two nodes A and B are required to transmit every frame separated byl. However, oscillator offset and drifts within the nodes force theframe length l to be time dependent and different for each node.Therefore, the transmit timestamp t_(B,Tx) ^((n)) is perceived by node Aas {tilde over (t)}_(A,Tx) ^((n)) due to clock discrepancies:{circumflex over ({tilde over (t)})}_(A,Tx) ^((n)) =t _(B,Tx) ^((n))+{circumflex over (T)} ^((n))  Equation 3

Also, frame length l measures to l_(A) and cycle separation L to L_(A)respectively on clock driving node A, which for the current cycle ofinterest become:{circumflex over (l)} _(A) ^((n-1))={circumflex over ({tilde over(t)})}_(A,Tx) ^((n)) −t _(A,Tx) ^((n-1))  Equation 4L _(A) ^((n-1)) =t _(A,Tx) ^((n-1)) −t _(A,Tx) ^((n-3))  Equation 5These formulations are used herein to aid delay and offset estimation.

Position states of the network nodes 20, 22 (e.g., node A and node B)can be estimated using an approach that not only synchronizes clocks onthe two network nodes 20, 22, but also estimates ToF between them. Forexample, a first-order Markov model using propagation delay τ and clocktime offset T can provide an optimal and time efficient position stateestimate. In addition, a second-order Markov model extends positionstate estimates to include radial acceleration ({umlaut over (τ)}) andclock frequency drift ({umlaut over (T)}). This accounts for any varyingradial acceleration between the network nodes 20, 22 (e.g., produced bythe flight path node B traverses).

Tracking Algorithm

With continuing reference to FIG. 3C, in an exemplary aspect, one ormore of the parameters described above (e.g., relative ToF between nodesA and B, relative radial velocity between nodes A and B, relative radialacceleration between nodes A and B, relative time offset between clocksA and B, relative frequency offset between clocks A and B, relativefrequency drift between clocks A and B) is tracked and used to improveposition state estimates. In some embodiments, the position stateestimates are tracked using a modified version of the extended Kalmanfilter (EKF) algorithm.

As suggested earlier, enough information to jointly estimate theparameters of interest are accrued only every cycle. An exemplary aspectdeploys tracking once every cycle and extrapolates these results toderive estimates for both the corresponding frames. The Kalman filteringmethod can be visualized as a two-step algorithm—1) Prediction and 2)Correction.

The prediction step can include an array of predictions made based onthe assumed models on transition of state and measurement parameters intime along with their error metrics. Using these predictions, statespace variables are corrected by evaluating a weighted sum of statepredictions and deviation of measurement predictions from observations.

With continuing reference to FIG. 3C, the transmit timestamp t_(B,Tx)^((n)) is perceived by node A as {tilde over (t)}_(A,Tx) ^((n)) andframe length l as l_(A) ^((n-1)) due to clock offset T. Exemplaryembodiments estimate these parameters as {circumflex over ({tilde over(t)})}_(B,Tx) ^(i,(n)) and {circumflex over (l)}_(A) ^(i,(n-1)) where iindicates the different methods (e.g., first order, second order) whoseestimates are shown in FIG. 3C. The joint offset and clocksynchronization approach is therefore extended with EKF tracking methodsthat track the position state estimates in time (e.g., delay, offset,radial acceleration, and clock frequency drift estimates, along withother parameters of interest).

HPPC Protocol and Waveform

FIG. 4A is a schematic diagram of interactions between network nodes 20,22 of the HPPC network 10 of FIG. 2 , illustrating an example protocolof the joint positioning-communications waveform. The first network node20 (node A) and the second network node 22 (node B) alternate betweentransmitting and receiving periodically over the jointpositioning-communications waveform. For example, at operation 400 nodeB receives a first signal from node A, which includes the jointpositioning-communications waveform. At operation 402, node B processesthe received data to produce an estimated position state, which caninclude estimating the ToA of all positioning sequences on all receivechannels (e.g., as described above with respect to FIGS. 3A-3C) andextracting timing information from a data payload of the jointpositioning-communications waveform.

In some examples, to support additional network nodes in the HPPCnetwork 10 without sacrificing quality of service, spatially adaptiveinterference mitigation techniques may also be employed at operation402. The multi-antenna nature of devices in the HPPC network 10 affordsspatial diversity that enables a variety of spatial interferencemitigation techniques. Adaptive techniques also allow the system toadapt to network nodes entering and exiting the network, time-varyingexternal interference, changing network environments, and evolvingchannels. The adaptive techniques may address the following:

1. Internal Interference: Adding network nodes to the HPPC network 10also increases the number of potential interferes that each mustmitigate. Due to the cooperative nature of this system, however,successive interference cancellation (SIC) techniques are a feasibleapproach to interference mitigation. SIC requires that a receiverreconstructs an estimate of an interfering signal, then subtract it fromthe signal it originally received. Network nodes within the HPPC network10 share information about how their waveforms are built, so thisreconstruction is tractable. Mutual interference may also be limited byadaptively coordinating power levels across the HPPC network 10 andadaptively scheduling time and frequency slots for different networknodes.

2. External Interference: The HPPC network 10 must also contend withalready congested spectral environments, in which it may not haveknowledge of the interferers. In this case, the spatial diversityafforded by the multi-antenna platforms may be leveraged to implementspatial beamforming, in which an antenna array is adjusted to maximizeincoming energy in the direction of other network nodes and minimizingincoming energy from the interferers. This process must also be adaptiveto compensate for interferers that move within the environment.

At operation 404, node B prepares a transmission, in which node Bassembles the position state information from operation 402 using thejoint positioning-communications waveform. At operation 406, node Btransmits the joint positioning-communications waveform back to node Ausing a second signal. Transmissions are scheduled by a master node(e.g., one of the first network node 20 and the second network node 22,or another node). In some examples, the transmissions occur every 50milliseconds (ms) (e.g., the cycle duration T_(cycle) is 50 ms). In someexamples, the joint positioning-communications waveform has a duration(T_(waveform)) of about 1 ms. This transfer of information drives thetiming synchronization and ToF estimation algorithm, as described abovewith respect to FIGS. 3A-3C.

Network operations for RF and other network devices (e.g., node A, nodeB) are governed by a suite of network protocols that define the systemoperations at multiple hierarchical levels. The most common model ofthis protocol suite is the Open Systems Interconnect (OSI) model, whichdivides the network protocols into 7 layers. These layers areresponsible for different levels of network operations, ranging from howdata is physically transferred through the network to how that data isused to implement applications.

These layers may be broadly categorized into 2 groups: media layers andhost layers. Media layers handle the transmission and reception of data,while the host layers handle routing that information to different usersand managing the network. FIGS. 4B and 4C illustrate exemplary data linklayer protocols for the HPPC network 10. FIG. 5 illustrates an exemplaryphysical layer protocol for the HPPC network 10. Additional embodimentsintegrate the HPPC network 10 into LTE, 5G, or other cellular networkprotocols. An exemplary approach to cellular integration using LTE medialayers is described below with respect to FIGS. 6A-6C.

FIG. 4B is a schematic diagram of an exemplary structure of a jointpositioning-communications waveform 32 using the protocol of FIG. 4A. Atransmission using the joint positioning-communications waveform 32includes a communications segment 34 and a positioning segment 36. Thecommunications segment 34 contains a data payload and several pilotsequences. In the exemplary joint positioning-communications waveform 32of FIG. 4B, a CDD strategy is used. The CDD strategy consists of placingan orthogonal positioning waveform on each antenna (Tx₁, Tx₂, Tx₃, Tx₄)and transmitting them simultaneously.

FIG. 4C is a schematic diagram of another exemplary structure of thejoint positioning-communications waveform 32 using the protocol of FIG.4A. In this example, a TDD strategy is used. The TDD strategy consistsof placing the same waveform on each antenna (Tx₁, Tx₂, Tx₃, Tx₄) buttransmitting in different time slots. CDD allows longer waveform whichincreases signal-to-noise ratio (SNR) relative to TDD, but must accountfor inter-symbol interference which may limit performance.

In the examples of FIGS. 4B and 4C, the joint positioning-communicationswaveform 32 contains a data payload 38, several positioning sequences 40for ToA estimation, a preamble 42, and post-ambles 44, 46 foracquisition and synchronization. The illustrated structure of the jointpositioning-communications waveform 32 is for a network node (e.g., thesecond network node 22 of FIG. 2 ) with 4 antennas. The first half ofthe waveform 32 contains the data payload 38 and supporting amblesequences 42, 44, 46. The data payload 38 can be placed between aminimum shift keying (MSK) preamble 42 and post-amble 44, which are usedby the receiver to acquire and synchronize the received waveform 32. Thedata payload 38 can be modulated using binary phase shift keying (BPSK).A second MSK post-amble 46 can be placed at the end of the waveform 32to enable precise frequency corrections.

The second half of the waveform 32 contains the positioning sequences40. These may be random MSK sequences that have been treated to have lowcross correlation properties with each other. One positioning sequence40 is transmitted from each transmit antenna (Tx₁ through Tx₄),following the CDD or TDD strategy. The TDD strategy can mitigateinter-symbol interference (ISI) at the receiver, which estimates the ToAof each sequence at each receive antenna. This further allows thereceiver to unambiguously estimate the path length to each transmitantenna. For two 4-antenna network nodes, there are 16 transmit-receivelinks that can be estimated.

In an exemplary aspect, the data payload 38 includes a position stateestimate, which can include delay, offset, radial acceleration, and/orclock frequency drift estimates, as well as relative range, position,velocity, acceleration, bearing, altitude, and/or orientation estimates.In some examples, the data payload 38 includes inertial information froman inertial navigation unit (which can include fused data from anaccelerometer, gyroscope, global positioning system (GPS) device,optical data from a camera, etc.). In other examples, the data payload38 can include distributed coherence information or beamforminginformation, which can be used to select antennas (e.g., where more thanfour antennas are available) and/or communication protocols which arebest for communication and/or position estimation.

FIGS. 4B and 4C are illustrated with the communications segment 34(including the data payload 38) transmitted from a first transmitantenna (Tx₁). It should be understood that embodiments of the jointpositioning-communications waveform 32 can transmit portions of thecommunications segment 34 (e.g., portions or all of the data payload 38)from any of the transmit antennas (Tx₁, Tx₂, Tx₃, Tx₄), or combinationsof the transmit antennas (including all of the transmit antennas).

FIG. 5 is a schematic diagram of physical layer components of the jointpositioning-communications waveform 32 of FIGS. 4B and 4C. The length ofeach component is defined in a number of critical samples, or chips. Inthis example, the communications segment 34 consists of a preamble 42(having a length of 128 chips), two post-ambles 44, 46 (each having alength of 128 chips), and a data payload 38 (having a length of 4064chips). The preamble 42 and post-ambles 44, 46 are used to estimatefrequency offsets for the communications processing chain.

The positioning segment 36 is a reserved segment that is occupiedaccording to the CDD strategy of FIG. 4B or the TDD strategy of FIG. 4C.Empty buffers 48 are placed between each component to mitigatemulti-path and inter-symbol interference.

LTE Protocol

LTE is the current state-of-the-art standard for mobile or cellularwireless communications. The salient feature of LTE is the usage oforthogonal frequency division multiplexing (OFDM) along with cyclicprefixing (CP) as a digital modulation scheme for data transmission.OFDM splits the channel bandwidth into multiple narrow sub-bands (orsub-carriers) and transmits data across multiple sub-carriers at thesame time. CP is a signal processing technique that takes an arbitrarynumber of samples from the end of an OFDM symbol and appends them to thebeginning of the symbol. This is done to ensure that the sub-carriersremain orthogonal to each other when passing through channels withmulti-path or frequency-selective fading. OFDM has many benefits, suchas:

-   -   Robust against frequency-selective fading and other narrow-band        interference.    -   Flexible transmission bandwidth support (by varying number of        sub-carriers used).    -   Increased spectral efficiency due to orthogonality between        sub-carriers.    -   Ability to multiplex in both time- and frequency-domain.

Each LTE subcarrier is set to be 15 kilohertz (kHz) wide. Thissub-carrier spacing was chosen to maintain a balance between the CPoverhead and sensitivity due to Doppler spread or multipath. Thissub-carrier spacing also means that the duration of an OFDM symbol is1/15000=66.7 microseconds (μs). In order to standardize transmissionschemes, LTE also defines a number of channel bandwidths that can beused:

-   -   1.4 MHz    -   3 MHz    -   5 MHz    -   10 MHz    -   15 MHz    -   20 MHz

LTE uses OFDM in both uplink and downlink transmission. However, despiteits many advantages, OFDM has certain drawbacks such as high sensitivityto high peak-to-average power ratio (PAPR). PAPR occurs due to randomconstructive addition of sub-carriers and results in spectral spreadingof the signal leading to adjacent channel interference.

It is a problem that can be overcome with high quality power amplifiersand amplifier linearization techniques. While these methods can be usedin a base station, they become expensive on mobile devices and otheruser equipments (UEs). Hence, UEs use a single carrier multiplexingscheme called single carrier frequency division multiple access(SC-FDMA) with CP on the uplink which reduces PAPR as there is only asingle carrier as opposed to multiple sub-carriers. This method is alsocalled discrete Fourier transform-spread OFDM (DFTS-OFDM) because it isthe same as using a discrete Fourier transform (DFT) pre-coder prior toOFDM modulation. In general, DFTS-OFDM behaves like a single-carriersystem with a short symbol duration compared to OFDM.

FIG. 6A is a schematic diagram of a structure of an LTE frame, which canbe adapted to include the joint positioning-communications waveform 32of the HPPC network 10 of FIGS. 1-5 . An LTE radio frame has a timeduration of 10 ms. Each frame is further divided into 10 sub-frames ofequal duration (1 ms). Each sub-frame includes two slots.

FIG. 6B is a schematic diagram of a structure of a slot in the LTE frameof FIG. 6A. Each sub-frame contains either 12 or 14 OFDM symbols,depending on whether a normal CP or extended CP is used. The typical LTEsub-frame consists of 14 OFDM symbols. Uplink and downlink scheduling isdone on a sub-frame basis. In the frequency domain, the number ofsub-carriers N ranges from 128 to 2048, depending on channel bandwidth,with 512 and 1024 for 5 MHz and 10 MHz, respectively, being mostcommonly used in practice.

FIG. 6C is a schematic diagram of resource blocks and resource elementsof the LTE frame of FIG. 6A. LTE transmission can be scheduled byresource blocks, each of which consists of 12 consecutive sub-carriers,or 180 kHz, for the duration of one slot (0.5 ms). This granularity isselected to limit signaling overhead. A resource element is the smallestdefined unit which consists of one OFDM sub-carrier during one OFDMsymbol interval. Each resource block consists of 12×7=84 resourceelements in case of normal CP (72 for extended CP).

Furthermore, the maximum transmit powers are defined in LTE as 46 dBmfor a base station and 23 dBm for UE. Additionally, within the OFDMsignal it is possible to choose between three types of modulation forthe LTE signal:

-   -   QPSK or 4-QAM (2 bits/symbol)    -   16-QAM (4 bits/symbol)    -   64-QAM (6 bits/symbol)

Within the LTE carrier bandwidth of up to 20 MHz, there are somesub-carriers that are faded and other are not faded. Transmission isdone using those frequencies that are not faded. LTE uplink and downlinkcan be operated either using frequency division duplexing (FDD) or TDD.In FDD mode of operation, the uplink and downlink are transmitted acrossseparate carrier frequencies, f_(UL) and f_(DL). Both the uplink anddownlink transmit one LTE frame or 20 OFDM symbols simultaneously.Isolation or separation between uplink and downlink are achieved byduplex filters. All LTE base stations operating in FDD can operate asfull-duplex transmitters/receivers. Guard intervals are used for UEdevices that can only operate at half-duplex, which have a typicalduration of 1 ms or 1 sub-frame. The range of carrier frequencies forLTE changes according to countries.

In TDD mode of operation, the uplink and downlink are transmitted acrossthe same carrier frequency. During one LTE frame, some sub-frames areallocated for uplink and some for downlink. Switching between uplink anddownlink transmission are done via a special sub-frame. The specialsub-frame has three distinct parts:

-   -   Downlink part: Used to transmit a small amount of LTE data.    -   Guard interval: Empty guard period. The duration depends on a        number of factors such as the size of the operating cell.    -   Uplink part: Smaller duration than the downlink part, used for        channel sounding, etc. No actual data is transferred in this        section.        Similar to FDD, the range of carrier frequencies for LTE changes        according to countries.

HPPC Integration with LTE

With continuing reference to FIGS. 6A-6C, integration of the jointpositioning-communications waveform 32 of the HPPC network 10 of FIGS.1-5 into the LTE standard is discussed. It should be understood thatthis is an illustrative embodiment of the HPPC network 10, and otherembodiments may be integrated into other communication protocols in asimilar manner.

Payload integration: The HPPC waveform was originally designed toaccommodate a specifically-sized payload. To integrate this payload intothe LTE standard, the size is adjusted and the payload is split intomultiple slots.

Embodiments of the joint positioning-communications waveform 32 of FIG.5 include a data payload 38 which is 8192 chips long. Each LTE slotcontains 7 OFDM symbols, each of which has a useful symbol length of2048 chips. The integrated data payload 38 must therefore be dividedinto at least 4 OFDM symbols. Depending on further additions to thecontent of the data payload 38, and to facilitate the receiver parsingthe received LTE frames, it may be beneficial to expand the data payload38 to cover all 7 OFDM symbols in a given slot. This would allow apayload length of 14336 chips, a 75% increase over the original jointpositioning-communications waveform 32, and simplifies the receive chainprocessing.

Positioning integration: The positioning sequences 40 of FIGS. 4B and 4Care independent sequences that are treated to have lowcross-correlations with each other. They do not necessarily need to betransmitted in sequence, as in FIG. 4C, as long as the transmit timesare recorded and shared. The standard OFDM symbols in an LTE slot are2192 chips long, which are already 119% longer than the positioningsequences 40, thus a single OFDM symbol should be sufficient for eachpositioning sequence 40.

There are only 7 symbols in an LTE slot, however, and given that thedata payload 38 must occupy at least 4 of the symbols, all of the datapayload 38 and all of the positioning sequences 40 cannot fit in asingle slot. It can therefore be assumed that a transmission occupies atleast 2 slots, preferably adjacent. If the jointpositioning-communications waveform 32 of the HPPC network 10 ismodified to fit 2 slots (14 OFDM symbols), then the LTE integration cansupport the following configurations:

-   -   Payload: 4 symbols, Positioning: 4 symbols, Extra: 6 symbols.        This configuration most closely matches the current HPPC        waveform design, with a slightly larger payload and doubly long        positioning sequences. There are 6 extra symbols during which        additional information can be added, such as pre- and        post-ambles or additional positioning sequences to support more        antennas.    -   Payload: 7 symbols, Positioning: 4 symbols, Extra: 3 symbols.        This configuration expands the communications payload to        accommodate more data as discussed above. This still leaves        enough room for 4 positioning sequences and 3 reserved symbols        for ambles or more antennas.

If the uplink can reserve two adjacent slots for the transmission of thepayload and positioning sequences, the system has flexibility in termsof placing and ordering the transmit waveforms. Given the configurationslisted above, reordering certain OFDM symbols may help mitigatemulti-path, inter-symbol interference, and time-frequency channelfading, as well as improve frequency offset estimates.

Frequency Offset Estimation: The HPPC system estimates frequency offsetsby placing a pre-amble and post-amble around the communications payload,and a second post-amble after the positioning sequences. Bothconfigurations above allow for these three sequences to be added atarbitrary locations, which may improve the frequency offset estimationby providing longer sequences to correlate and a large separation toreduce the estimator variance.

An alternative to using the pre-amble and post-ambles is to use the CPof the OFDM symbols to perform the carrier frequency offset estimation.Depending on the necessary precision, this may be sufficient forestimating the offset without the need for any additional pilotsequences, which allows the extra symbols to support increased datathroughput or additional platform antennas.

Resource Allocation: Some embodiments of the HPPC system are defined asa point-to-point positioning-communications system, and therefore lack aprotocol for distributing spectral and temporal access for largenetworks of users. The LTE standard defines how uplink and downlinktransmissions are scheduled, and how different users are granted accessto time-frequency resource elements. An integrated LTE HPPC data linklayer must address the following concerns in this regard:

-   -   Time Slots: As discussed in a previous section, an HPPC network        node needs two consecutive slots (2×0.5 ms) to complete a        transmission. It can be assumed that all HPPC traffic is        considered uplink traffic by the LTE network, and as such the        integrated data link layer schedules uplink/downlink according        to this constraint.    -   Frequency Slots: The RF receiver in an HPPC network node is        sensitive to interference from nearby frequency bands. It is        likely that nearby users operating in adjacent frequency        allocations will interfere with each other, so the data link        layer distributes HPPC traffic to avoid co-channel interference.    -   Traffic Dependent Scheduling: Depending on the volume of HPPC        traffic, the data link layer may decide to allow a user to        transmit over more than one frequency bin to increase throughput        and positioning performance. A protocol is provided that        identifies the available resources and appropriately allocates        them.    -   Channel Dependent Scheduling: Because LTE operates over such a        large frequency range, it is possible that some users may        experience significantly greater fading in some frequency bins        than others. If the network traffic is sufficiently low, it is        possible to adaptively reallocate frequency slots to different        users to maximize overall performance.

Network layer: For applications where network nodes are frequentlyentering and leaving the HPPC network 10, a network protocol can beautomated to register users to maintain network performance andstability. This includes protocols that authenticate entrants andregister them with the data link layer protocols, and removes them oncethey leave the area or their session ends.

Many potential HPPC applications require distribution of knowledgethroughout the network, even between network nodes that do not share adirect link. The network layer protocols handle transfer of suchinformation and how that traffic is managed. An integrated data linklayer must define how this information is routed throughout the network,how to service each network node with as few resources as possible, andhow to reduce redundancy to mitigate congestion.

FIG. 7 is a schematic diagram of a generalized representation of anexemplary computer system 700 that could be used to perform any of themethods or functions described herein, such as receiving, processing,and/or sending joint positioning-communications waveforms. In someexamples, a network node 20, 22 in the HPPC network 10 of FIGS. 1 and 2is implemented as the computer system 700. In this regard, the computersystem 700 may be a circuit or circuits included in an electronic boardcard, such as, a printed circuit board (PCB), a server, a personalcomputer, a desktop computer, a laptop computer, an array of computers,a personal digital assistant (PDA), a computing pad, a mobile device, orany other device, and may represent, for example, a server or a user'scomputer.

The exemplary computer system 700 in this embodiment includes aprocessing device 702 or processor (e.g., the signal processor 30 ofFIG. 2 ), a main memory 704 (e.g., read-only memory (ROM), flash memory,dynamic random access memory (DRAM), such as synchronous DRAM (SDRAM),etc.), and a static memory 706 (e.g., flash memory, static random accessmemory (SRAM), etc.), which may communicate with each other via a databus 708. Alternatively, the processing device 702 may be connected tothe main memory 704 and/or static memory 706 directly or via some otherconnectivity means. In an exemplary aspect, the processing device 702could be used to perform any of the methods or functions describedabove.

The processing device 702 represents one or more general-purposeprocessing devices, such as a microprocessor, central processing unit(CPU), or the like. More particularly, the processing device 702 may bea complex instruction set computing (CISC) microprocessor, a reducedinstruction set computing (RISC) microprocessor, a very long instructionword (VLIW) microprocessor, a processor implementing other instructionsets, or other processors implementing a combination of instructionsets. The processing device 702 is configured to execute processinglogic in instructions for performing the operations and steps discussedherein.

The various illustrative logical blocks, modules, and circuits describedin connection with the embodiments disclosed herein may be implementedor performed with the processing device 702, which may be amicroprocessor, field programmable gate array (FPGA), a digital signalprocessor (DSP), an application-specific integrated circuit (ASIC), orother programmable logic device, a discrete gate or transistor logic,discrete hardware components, or any combination thereof designed toperform the functions described herein. Furthermore, the processingdevice 702 may be a microprocessor, or may be any conventionalprocessor, controller, microcontroller, or state machine. The processingdevice 702 may also be implemented as a combination of computing devices(e.g., a combination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration).

The computer system 700 may further include a network interface device710. The computer system 700 also may or may not include an input 712,configured to receive input and selections to be communicated to thecomputer system 700 when executing instructions. The input 712 mayinclude, but not be limited to, a touch sensor (e.g., a touch display),an alphanumeric input device (e.g., a keyboard), and/or a cursor controldevice (e.g., a mouse). In an exemplary aspect, the RF transceiver 24 ofFIG. 2 is an input 712 to the computer system 700. The computer system700 also may or may not include an output 714, including but not limitedto a display, a video display unit (e.g., a liquid crystal display (LCD)or a cathode ray tube (CRT)), or a printer. In some examples, some orall inputs 712 and outputs 714 may be combination input/output devices.In an exemplary aspect, the RF transceiver 24 of FIG. 2 is also anoutput 714 of the computer system 700.

The computer system 700 may or may not include a data storage devicethat includes instructions 716 stored in a computer-readable medium 718.The instructions 716 may also reside, completely or at least partially,within the main memory 704 and/or within the processing device 702during execution thereof by the computer system 700, the main memory704, and the processing device 702 also constituting computer-readablemedium. The instructions 716 may further be transmitted or received viathe network interface device 710.

While the computer-readable medium 718 is shown in an exemplaryembodiment to be a single medium, the term “computer-readable medium”should be taken to include a single medium or multiple media (e.g., acentralized or distributed database, and/or associated caches andservers) that store the one or more sets of instructions 716. The term“computer-readable medium” shall also be taken to include any mediumthat is capable of storing, encoding, or carrying a set of instructionsfor execution by the processing device 702 and that causes theprocessing device 702 to perform any one or more of the methodologies ofthe embodiments disclosed herein. The term “computer-readable medium”shall accordingly be taken to include, but not be limited to,solid-state memories, optical medium, and magnetic medium.

The operational steps described in any of the exemplary embodimentsherein are described to provide examples and discussion. The operationsdescribed may be performed in numerous different sequences other thanthe illustrated sequences. Furthermore, operations described in a singleoperational step may actually be performed in a number of differentsteps. Additionally, one or more operational steps discussed in theexemplary embodiments may be combined.

Those skilled in the art will recognize improvements and modificationsto the preferred embodiments of the present disclosure. All suchimprovements and modifications are considered within the scope of theconcepts disclosed herein and the claims that follow.

What is claimed is:
 1. A method for receiving and processing joint positioning and communications, the method comprising: receiving a first signal comprising a joint positioning-communications waveform from a network node, the joint positioning-communications waveform comprising: a preamble; a data payload, wherein the data payload of the first signal comprises a first position state of the network node; a first positioning sequence; and a second positioning sequence; and estimating a second position state relative to the network node from the first signal.
 2. The method of claim 1, wherein the second position state is estimated based on the first positioning sequence and the second positioning sequence.
 3. The method of claim 2, wherein the second position state is further estimated based on the first position state.
 4. The method of claim 2, wherein: the joint positioning-communications waveform further comprises: a third positioning sequence; and a fourth positioning sequence; and the second position state is further estimated based on the third positioning sequence and the fourth positioning sequence.
 5. The method of claim 1, wherein: receiving the first signal comprises receiving the first signal at each of a plurality of antennas; and estimating the second position state comprises using estimating a time of flight from the network node to each of the plurality of antennas using the first positioning sequence and the second positioning sequence.
 6. The method of claim 1, wherein the first positioning sequence is received simultaneously with the second positioning sequence.
 7. The method of claim 1, wherein the second positioning sequence is received sequentially after the first positioning sequence.
 8. The method of claim 1, wherein the joint positioning-communications waveform further comprises: a first post-amble sequenced between the data payload and the first positioning sequence; and a second post-amble sequenced after the second positioning sequence.
 9. The method of claim 1, further comprising transmitting a second signal comprising the joint positioning-communications waveform in which the data payload comprises the second position state.
 10. The method of claim 9, wherein transmitting the second signal comprises: transmitting the first positioning sequence from a first antenna; and transmitting the second positioning sequence from a second antenna.
 11. The method of claim 10, wherein transmitting the second signal further comprises transmitting the preamble and the data payload from the first antenna.
 12. The method of claim 10, wherein the first positioning sequence is transmitted simultaneously with the second positioning sequence.
 13. The method of claim 10, wherein the second positioning sequence is transmitted sequentially after the first positioning sequence.
 14. The method of claim 10, wherein transmitting the second signal comprising the joint positioning-communications waveform further comprises: transmitting a third positioning sequence from a third antenna; and transmitting a fourth positioning sequence from a fourth antenna.
 15. The method of claim 10, wherein the joint positioning-communications waveform further comprises: a first post-amble sequenced between the data payload and the first positioning sequence; and a second post-amble sequenced after the second positioning sequence.
 16. The method of claim 9, wherein the data payload of the second signal comprises additional information.
 17. The method of claim 16, wherein the additional information comprises inertial information received from at least one of an inertial navigation unit, an accelerometer, a gyroscope, a global positioning system (GPS) device, or a camera.
 18. The method of claim 17, wherein the additional information comprises at least one of distributed coherence information or beamforming information based on the second position state.
 19. A network for joint positioning and communications, the network comprising: a first network node, comprising: a first signal transceiver configured to communicate wirelessly with a second network node; and a first signal processor operable to: estimate a first position state of the first network node relative to the second network node; generate a joint positioning-communications waveform comprising: a preamble; a data payload; a first positioning sequence; and a second positioning sequence; and cause the first signal transceiver to transmit a first signal comprising the joint positioning-communications waveform, wherein the data payload of the first signal comprises the first position state.
 20. The network of claim 19, further comprising: the second network node, comprising: a second signal transceiver configured to communicate wirelessly with the first network node; and a second signal processor operable to: receive the first signal from the first network node; estimate a second position state of the second network node relative to the first network node from the first signal; and cause the second signal transceiver to transmit a second signal comprising the joint positioning-communications waveform, wherein the data payload of the second signal comprises the second position state. 